27,387 research outputs found
Topological Quantum Field Theory and Seiberg-Witten Monopoles
A topological quantum field theory is introduced which reproduces the
Seiberg-Witten invariants of four-manifolds. Dimensional reduction of this
topological field theory leads to a new one in three dimensions. Its partition
function yields a three-manifold invariant, which can be regarded as the
Seiberg-Witten version of Casson's invariant. A Geometrical interpretation of
the three dimensional quantum field theory is also given.Comment: 15 pages, Latex file, no figure
Bioprocesses
The application of remote sensing techniques to the study of eutrophication in natural waters and the location and characterization of fronts is considered. The specific problem to be studied is examined along with the feasibility and capabability of remote sensing techniques for each application
RF free ultrasonic positioning
All wearable centric location sensing technologies must address the issue of clock synchronisation between signal transmitting systems and signal receiving systems. GPS receivers, for example, compensate for synchronisation errors by incorporating a model of the receiver clock offset in the navigation solution. Drift between satellite clocks is also monitored to keep signal data in synch with GPS time. Most ultrasonic positioning systems solve the synchronisation problem by using a second medium for communication between transmitter and receiver devices. The transmitters in these systems emit RF signals (pings) to indicate the transmission of subsequent ultrasound signals (chirps). By subtracting the arrival time of the ping from that of the chirps, the receiver is able to compute the distance to each transmitter. In this paper, we describe an ultrasonic positioning system that does not use RF signals to achieve synchronisation. Instead, it exploits a periodic chirp transmission pattern to model the receiver’s position using chirp reception times exclusively. Not only does the system improve on the accuracy of previous technologies but it also eliminates bulky RF circuitry – a definite advantage for wearable applications where component size and weight are critical for usability.
Does woman + a network = career progression?
Question: I am an ambitious and talented junior manager who has recently been hired by FAB plc, a large multinational company. I am also a woman and, as part of my induction pack, have received an invitation to join FABFemmes - the in-company women's network. I don't think my gender has been an obstacle to my success thus far and so I don't really feel the need to join. But on the other hand I don't want to turn my back on something that might offer me a useful source of contacts to help me advance up the career ladder. What would be the best thing to do? - Ms Ambitious, UK
Interdisciplinary research on the application of ERTS-1 data to the regional land use planning process
The author has identified the following significant results. Although the degree to which ERTS-1 imagery can satisfy regional land use planning data needs is not yet known, it appears to offer means by which the data acquisition process can be immeasurably improved. The initial experiences of an interdisciplinary group attempting to formulate ways of analyzing the effectiveness of ERTS-1 imagery as a base for environmental monitoring and the resolution of regional land allocation problems are documented. Application of imagery to the regional planning process consists of utilizing representative geographical regions within the state of Wisconsin. Because of the need to describe and depict regional resource complexity in an interrelatable state, certain resources within the geographical regions have been inventoried and stored in a two-dimensional computer-based map form. Computer oriented processes were developed to provide for the economical storage, analysis, and spatial display of natural and cultural data for regional land use planning purposes. The authors are optimistic that the imagery will provide revelant data for land use decision making at regional levels
The use of ERTS-1 data for the inventory of critical land resources for regional land use planning
Computer-generated spatial and statistical comparisons of critical land resource data derived from conventional sources, RB-57 photographs, and ERTS images, for an eastern Wisconsin test site, suggest that certain critical land resource data can be mapped from ERTS images on a statewide basis. This paper presents one of the biotic resources, wetlands, as an example of the use of ERTS imagery to inventory land resources
The experience of enchantment in human-computer interaction
Improving user experience is becoming something of a rallying call in human–computer interaction but experience is not a unitary thing. There are varieties of experiences, good and bad, and we need to characterise these varieties if we are to improve user experience. In this paper we argue that enchantment is a useful concept to facilitate closer relationships between people and technology. But enchantment is a complex concept in need of some clarification. So we explore how enchantment has been used in the discussions of technology and examine experiences of film and cell phones to see how enchantment with technology is possible. Based on these cases, we identify the sensibilities that help designers design for enchantment, including the specific sensuousness of a thing, senses of play, paradox and openness, and the potential for transformation. We use these to analyse digital jewellery in order to suggest how it can be made more enchanting. We conclude by relating enchantment to varieties of experience.</p
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Making Sense of Family Deaths in Urban Senegal: Diversities, Contexts, and Comparisons
Despite calls for cross-cultural research, Minority world perspectives still dominate death and bereavement studies, emphasizing individualized emotions and neglecting contextual diversities. In research concerned with contemporary African societies, on the other hand, death and loss are generally subsumed within concerns about AIDS or poverty, with little attention paid to the emotional and personal significance of a death. Here, we draw on interactionist sociology to present major themes from a qualitative study of family deaths in urban Senegal, theoretically framed through the duality of meanings-in-context. Such themes included family and community as support and motivation; religious beliefs and practices as frameworks for solace and (regulatory) meaning; and material circumstances as these are intrinsically bound up with emotions. Although we identify the experience of (embodied, emotional) pain as a common response across Minority and Majority worlds, we also explore significant divergencies, varying according to localized contexts and broader power dynamics
NICMOS observations of high redshift radio galaxies: witnessing the formation of bright elliptical galaxies?
We present the results of a near infrared imaging program of a sample of 19
radio galaxies with redshift between 1.7 and 3.2, using the NICMOS Camera 2 on
the Hubble Space Telescope. The galaxies were observed in H-band which, for 18
of the 19 targets, samples the rest-frame optical emission longwards of the
4000 A break. The images show a wide range of morphologies, from unresolved to
compact systems, to systems with substructures such as multiple emission peaks,
to systems comprised of several components spread over large areas. The
morphologies of 5 of the lowest redshift targets are well represented by a de
Vaucouleurs profile, consistent with them being elliptical galaxies. Their
average effective radius is a factor of 2 smaller than that of z=1 3CR radio
galaxies at similar restframe wavelengths. The near infrared continuum light is
generally well aligned with the radio axis and the aligned light has typical
V-H colors of around 3.5-4. For several galaxies where WFPC2 images were
available, we computed a high resolution map of the optical-to-infrared
spectral indices: all multi-component systems present net color gradients
between the various clumps. We argue that in these galaxies the continuum
emission has probably a stellar origin. Finally in many cases we observe nearby
faint objects close to the radio sources. The number density of these faint
objects is slightly higher than what is found in the deep NICMOS parallel
observations of random fields. These objects also tend to be aligned with the
radio sources axis, suggesting that they may be related to the presence of the
AGN. (shortened astro-ph version)Comment: To appear in ApJ
Advanced tracking systems design and analysis
The results of an assessment of several types of high-accuracy tracking systems proposed to track the spacecraft in the National Aeronautics and Space Administration (NASA) Advanced Tracking and Data Relay Satellite System (ATDRSS) are summarized. Tracking systems based on the use of interferometry and ranging are investigated. For each system, the top-level system design and operations concept are provided. A comparative system assessment is presented in terms of orbit determination performance, ATDRSS impacts, life-cycle cost, and technological risk
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